On Sat, 2018-01-13 at 08:19 +1100, Dave Chinner wrote: : > IOWs, what you are seeing is trying to do a very large allocation on > a very small (8GB) XFS filesystem. It's rare someone asks to > allocate >25% of the filesystem space in one allocation, so it's not > surprising it triggers ENOSPC-like algorithms because it doesn't fit > into a single AG.... > > We can probably look to optimise this, but I'm not sure if we can > easily differentiate this case (i.e. allocation request larger than > continguous free space) from the same situation near ENOSPC when we > really do have to trim to fit... > > Remember: stripe unit allocation alignment is a hint in XFS that we > can and do ignore when necessary - it's not a binding rule. Thanks for the clarification! Can XFS allocate smaller extents so that each extent will fit to an AG? ext4 creates multiple smaller extents for the same request. -Toshi
